Radiation images formed using a film have been widely used heretofore at the medical site. However, a radiation image formed using a film presents analog image information. Thus, in recent years, digital-type radiation detectors such as computed radiographies (CR) and flat panel detectors (hereinafter, referred to as “FPD”) have been developed.
In the FPD, a scintillator panel is used for converting a radiation into visible light. The scintillator panel includes a radiation phosphor. The radiation phosphor emits visible light in response to an applied radiation, and the emitted light is converted into an electric signal by a TFT (thin film transistor) or a CCD (charge-coupled device) to convert information of the radiation into digital image information. However, the FPD has the problem that at the time when the radiation phosphor emits light, visible light is scattered by the radiation phosphor itself, leading to a decrease in S/N ratio.
A method has been proposed in which for reducing influences of scattering of emitted light, a phosphor is separated by barrier ribs, more specifically a phosphor is packed into spaces, i.e. cells, which are separated by preformed barrier ribs. As a method for preforming barrier ribs, etching processing of a silicon wafer, a screen printing method using a glass powder-containing paste, or a photosensitive paste is known (Patent Documents 1 to 4). On the other hand, a method is known in which a single crystal of a phosphor is mechanically processed to form a groove, and barrier ribs are embedded in this groove (Patent Document 5).